1. Field of the Invention
The present invention relates to an information storage medium which stores digitally broadcasted video and audio signals. The present invention also relates to an information recording apparatus for recording, on an information storage medium, video and audio signals and the like distributed by digital broadcasting.
2. Description of the Related Art
Digital broadcasting is the recent trend in TV broadcasting, and the necessity of streamers for recording digital broadcasting is acknowledged.
Currently, MPEG-TS (Moving Picture image coding Experts Group-Transport Stream) defined by the MPEG standard is employed as the data transfer scheme in digital TV broadcasting in Japan, America, and Europe. The MPEG-TS scheme is projected to be the standard in the field of digital broadcasting using moving images.
Currently, as a device for recording digital broadcast data sent by MPEG-TS, D-VHS (Digital-Video Home System) using a tape as a recording medium is commercially available. However, from the viewpoint of accessibility, a device using an optical disk as a recording medium is demanded.
Digital TV broadcasting is sent from a broadcast station via a communication satellite and received and played back by an STB (Set Top Box). The STB is an apparatus which expands and plays back scrambled data on the basis of a key code supplied from the broadcast station. The data is scrambled to prevent any illicit reception by users who are not subscribers of that broadcast station.
In the STB, digital data is received by a tuner system. To directly play back the received data, the data is descrambled by a digital expansion section, decoded by an MPEG decoder section, converted into a TV signal by a video encoder section, and displayed on a TV.
To stream broadcast data, digital data received from the tuner system is recorded on a D-VHS through an IEEE (the Institute of Electrical and Electronics Engineers) 1394 I/F. IEEE 1394 is an interface standard for command exchange and data transmission/reception.
To play back recorded broadcast data, the data is read from the D-VHS, sent to the data expansion section in the STB, and played back.
In the D-VHS streamer, however, the broadcast bit stream is directly recorded on the tape. Hence, a plurality of programs are multiplexed and recorded on the tape. In the playback mode, all data is sent regardless of whether a program is to be played back from the beginning or halfway. The STB selectively plays back a desired program.
In addition, since programs are recorded on a tape medium, random access is impossible. It is therefore difficult to quickly jump to a desired position of a desired program and play it back.
To do this, a streamer standard using a large-capacity disk medium such as a current DVD (Digital Versatile Disk)-RAM is suggested.
Digital broadcasting by ground waves is expected to start in several years. Free digital broadcasting will start. This will be done as non-scrambled broadcasting.
The streamer standard aims at processing scrambled broadcasting data at various broadcast stations all over the world. The minimum playback unit in video contents is a data amount based on an ECC block. For this reason, in a special playback mode, even when data is read from a target address, no I picture that can be played back is found. Hence, the start of playback may largely shift. That is, it is very difficult to perform special playback in this standard.
A standard that lays out PAT (Program Association Table) or PMT (Program Map Table) at the start of video contents is described in Jpn. Pat. Appln. KOKAI Publication No. 2000-268537. However, in this prior art or in the streamer standard, since there is no TMAP information as in DVD-VR, processing is incompatible with DVD-VR.
In a streamer system compatible with digital TV broadcasting, fine management cannot be executed in special playback of video content data.